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Finding the Fourth Proportional to 811.92, 1,215.90 and 379.20

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Solution

The fourth proportional to 811.92, 1,215.90 and 379.20 is: 567.88

Step by Step Solution

  1. Step 1: Write the proportion equation
    811.92 : 1,215.90 = 379.20 : x
  2. Step 2: Convert to fraction form
    811.92/1,215.90 = 379.20/x
  3. Step 3: Cross multiply
    811.92x = 1,215.90 × 379.20
  4. Step 4: Simplify right side
    811.92x = 461,069.28
  5. Step 5: Solve for x
    x = 461,069.28/811.92
  6. Step 6: Final answer
    x = 567.88

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.